Effect of baseline carbohydrate antigen 19-9 (CA19-9) level on overall survival (OS) in NAPOLI-1: A randomized phase III study of MM-398 (nal-IRI), with or without 5-fluorouracil and leucovorin (5-FU/LV), versus 5-FU/LV in metastatic pancreatic cancer (mPAC) previously treated with gemcitabine (gem)-based therapy.

425 Background: CA19-9 has been shown to correlate with response to therapy and OS in patients with mPAC. NAPOLI-1, a randomized phase 3 study evaluated nal-IRI, a nanoliposomal formulation of irinotecan, with or without 5-FU/LV vs 5-FU/LV in patients with mPAC previously treated with gemcitabine-based therapy. Nal-IRI+5-FU/LV significantly improved OS (primary endpoint) vs 5-FU/LV (6.1 mo vs 4.2 mo; unstratified hazard ratio [HR] = 0.67; P = 0.012). CA19-9 response (≥50% decline from baseline) was superior with nal-IRI+5FU/LV compared with 5-FU/LV (29% vs 9%; P=0.0006). Nal-IRI alone did not show a statistical improvement in survival. Methods: Patients with a recorded baseline CA19-9 measurement were divided into quartiles to evaluate the treatment effect pattern of CA19-9 from nal-IRI+5-FU/LV and 5-FU/LV arms. Quartile ranges were based on 404 available CA19-9 values from randomized patients (N=417). Unstratified Cox proportional hazards regression was used to estimate HRs and corresponding 95% CIs. Eff...